As generally known to those having ordinary skill in the art, a battery cell, which is used to supply electrical energy, stores the electrical energy therein or discharges the electrical energy therefrom during the charging or discharging of the battery cell.
When the battery cell is over-discharged, the lifespan and the durability of the battery cell may be reduced due to an energy consumption characteristic. When the battery cell is overcharged, a risk to safety may be caused due to an energy accumulation characteristic.
When the battery cell is overcharged, gas may be generated and a temperature may be increased in the battery cell. Accordingly, the battery cell may be swollen and exploded, which is referred to as a swelling phenomenon.
Accordingly, a safety circuit against the overcharge is provided in the battery cell such that the battery cell is charged up until a point at which the battery cell is ignited or exploded. Accordingly, fail-safe operation may be ensured for the safety of a customer.
Meanwhile, a pouch type battery cell may include an electrode assembly, a thin-plate pouch which encloses the electrode assembly, and a lead tap connected with the electrode assembly.
In addition, a plurality of battery cells may be connected with bus bars to make battery modules.
Such a battery module may include a current interrupt device (CID), a kind of safety circuit. The CID disconnects the electrode assembly from the lead tap to interrupt the flow of the current when the battery cell is overcharged and when the pouch swells.